From the Guidelines
The apparatus for the mitral and tricuspid valves consists of the valve leaflets, annulus, chordae tendineae, and papillary muscles. The mitral valve has two leaflets (anterior and posterior) while the tricuspid valve has three leaflets (anterior, posterior, and septal) 1. Both valves are anchored by chordae tendineae, which are thin, fibrous cords that connect the valve leaflets to papillary muscles projecting from the ventricular walls. The mitral valve typically has two main papillary muscles (anterolateral and posteromedial), while the tricuspid valve has three papillary muscles 1. This apparatus works together to prevent backflow of blood during cardiac contraction. When the ventricles contract, blood pressure increases and would force the valves to invert into the atria, but the chordae tendineae and papillary muscles tense to hold the valve leaflets in position, allowing them to close properly without prolapsing. Some key points to consider about these valves include:
- The type of prosthesis used for replacement, such as mechanical or bioprosthetic valves, can affect the risk of thromboembolism and the need for anticoagulation 1.
- The choice of prosthesis may depend on factors such as the patient's age, lifestyle, and underlying medical conditions 1. Dysfunction in any component of this apparatus can lead to valve regurgitation or stenosis, causing symptoms of heart failure. In cases of significant tricuspid regurgitation, annuloplasty or valve replacement with a biological prosthesis may be necessary 1.
From the Research
Apparatus for Mitral and Tricuspid Valve
The apparatus for mitral and tricuspid valve replacement can be either mechanical or bioprosthetic.
- Mechanical valves are made of artificial materials and require lifelong anticoagulation therapy to prevent blood clots from forming on the valve 2.
- Bioprosthetic valves are made from animal tissue or human donor tissue and do not require long-term anticoagulation therapy, but may deteriorate over time and require replacement 2.
Comparison of Mechanical and Bioprosthetic Valves
Studies have compared the outcomes of mechanical and bioprosthetic valves in the tricuspid and mitral positions.
- A systematic review and meta-analysis found that mechanical and bioprosthetic valves had similar risks of 30-day and late mortality, reoperation, and 5-year valve failure in patients undergoing tricuspid valve replacement 3.
- Another study found that mechanical valves were associated with lower long-term mortality and fewer mitral reoperations, but a greater risk of major bleeding events, stroke, and systemic embolism compared to bioprosthetic valves in patients undergoing mitral valve replacement 2.
- A study comparing clinical and echocardiographic outcomes after tricuspid valve replacement found that mechanical and bioprosthetic valves provided comparable survival, incidence of reoperation, and recovery of right ventricular systolic function and size, but bioprosthetic valves developed significant tricuspid regurgitation over time 4.
Valve Selection
The choice of valve type depends on various factors, including patient age, lifestyle, and medical history.
- Mechanical valves may be preferred for younger patients or those who can tolerate long-term anticoagulation therapy 4.
- Bioprosthetic valves may be preferred for older patients or those who cannot tolerate anticoagulation therapy 2.
- The decision to use a mechanical or bioprosthetic valve should be made on a case-by-case basis, taking into account the individual patient's needs and preferences 3, 2, 4.